Insecticide and method for its distribution

ABSTRACT

A new method for controlling insects on plants is provided which comprises applying a composition comprising a chemical insecticide an an insecto-pathogenic fungus product which had been cultured on a substrate such as bran, whole meal, oatmeal and the like. The insecticidal compositions contain a combination of chemical insecticide and an insecto-pathogenic fungus.

This is a continuation of Ser. No. 724,803, filed Apr. 19, 1985, nowabandoned, which is a continuation of Ser. No. 194,864, filed Oct. 7,1980, now abandoned, which is a continuation of Ser. No. 887,890, filedMar. 20, 1978, now abandoned, which is a continuation of Ser. No.709,892, filed July 29, 1976, now abandoned.

The invention described in the following concerns a method of pestcontrol by spraying on or powdering on a pesticide which is acombination of micro organisms and chemical insecticides, and an agentfor the application of this method.

In the beginning of the forties the first insecticides on a chemicalbase were used in agriculture on a large scale. It was especially DDTwhich proved to be successful. Unfortunately symptoms of resistanceagainst this agent showed up very soon. In the fifties the commonhousefly became resistant to DDT. Later on, other harmful insects, suchas the potatoe beetle, the blossom rape beetle (meligethes aeneus) andthe beet root weevil (bothynoderes punctiventris) became resistant toDDT, too. However, the agent was not only used in agriculture, but wasapplied almost universally. Clothings and a further series of commodityarticles, packing material, cosmetics, etc., were preserved by means ofDDT.

It is true that at the beginning small amounts of the agent weresufficient. However, in the fifties, the above mentioned symptoms ofresistance necessitated an increase of the chemical base of theinsecticide; the agents were more heavily chlorinated and thechlorinated insecticides Chlordane Heptachlor, Methoxychlor, Aldrin,Dieldrin and Lindan were developed. Very soon symptoms of resistanceshowed up against the phosphoric esters too, which had been developpedlater on.

As a consequence of this development more and more concentrated baseswere used. This, however, entailed symptoms of poisoning in warm-bloods.Thus the insecticides on a chemical base began to show as dangerousneurotoxins and as cumulating agents causing damages of liver and heartand being cumulated in the adipose tissue. This not only in men, butalso in domestic animals, the insecticides thus being re-fed to men viathe nourishment.

Efforts to counteract the resistance by combining insecticides withdifferent chemical bases remained without success. In any case thesymptoms of poisoning did not disappear.

All attempts to counteract the resistance proved to be a failure. Newchemical insecticides were developed continually, thus entailing anavalanchelike development of new agents, which--quite apart from theharmful effects--consumed much time and money.

We must realize that we cannot go on developing new insecticidesinterminately.

Therefore it is an urgent problem to develop methods of pest controlwhich are harmless and not subject to phenomena of resistance.

It is well known that pesticides can be prepared from a mixture of microorganisms of the genus bacillus with synthetic pyrethroid insecticides.The action of pesticides of this kind is based on a synergistic effect,which has the disadvantage that the pests get resistant to the agentafter some time.

About ten years ago a new insecticide on a biological base was developedby an Austrian research team. This insecticide is an agent made up offungi of the classical muscardine type, such as Beauveria bassiana,Beauveria tenella, Paecilomyces farinosus and Metarrhizium anisopliae.The fungi act in an insecto-pathogenic way, i.e. the dried andcomminuted material of fungi as well as the spores have infectiousqualities. However, the dried material of fungi is richer in enzymes andtoxic compounds.

The development of pest control on a biological base presented a methodwhich was absolutely harmless to warm-bloods. It was proved that nosymptoms of poisoning turned up. However, it was difficult to culturesufficient quantities of the fungi. It is true that with the use ofinsecto-pathogenic fungi np symptoms of resistance showed up, however,the mortality rate in insects was not sufficiently high. Thereforeattempts were made to use the fungi in combination with bacilli. Thuse.g. Beauveria bassiana was used against the corn weevil in combinationwith the Bacillus thuriengiensis. For the control of potatoe beetles andgreenflies Beauveria bassiana was combined with Metarrhizium anisopliaeon the one hand and Paecilomyces farinosus with Metarrhizium anisopliaeon the other hand.

There exists a series of insects with a special power of resistance tochemical insecticides as well as insecticides on a biological base. Thusit is almost impossible till now to get the potatoe beetle undercontrol. In the United States a special procedure on a biological basewith the aid of ladybird beetles had to be used.

The invention on hand presents the development of a new method, based onthe combination of chemical insecticides and insecto-pathogenic fungi.The method according to the invention consists in the combination of achemical insecticide with an insecto-pathogenic fungus cultured onsubstrates such as bran, whole meal, oat meal and the like.

The method according to the invention may be carried out in such a wayas to infect the cultures at first with the chemical insecticide inorder to achieve a weakening of the pest; after that the pest isdestroyed by application of the mycelium. However, it is also possibleto prepare a mixture of the chemical insecticide and the mycelium and toapply this mixture.

The pest control agent according to the invention consists of preferably0.2-2 parts by weight of mycelium and 0.01-0.0001 parts by weight ofinsecticide. It has proved successful to spray on a solution of theagent according to the invention as well as to powder it on in its solidform. In the first case the usual solution is prepared with water, towhich wetting agents are added. In the second case the agent accordingto the invention is mixed with powdered talc and dusted on the cultures.A combined application, i.e. dusting on one of the components in itssolid form and spraying on a solution of the other component is alsopossible within the framework of the present invention.

According to the invention almost any chemical insecticide developedtill now may be used. Thus e.g. the chlorinated aromatic compounds, suchas DDT, benzene hexachloride, Chlordan, Metoxychlor, Heptachlor,Dieldrin, Aldrin, Endrin, the phosphoric esters, such as Phosdrin,Metasystox, Birlane, E 605 and Gusathion.

Examples for insecto-pathogenic fungi are especially those of the classof phycomycetes, such as Entomophtora spaerosperma, Empusa muscae,Empusa aulicae as well as those of the class of ascomycetes, such asBeauveria bassiana, Beauveria tenella, Paecilomyces fumosoroseus,Paecilomyces farinosus and Metarrhizium anisopliae.

By the combination of micro organism or fungus, resp., with chemicalinsecticides a potentiation of the initial effect is brought about. Thisis not due to a synergism as it is the case with the combination ofchemical insecticides or the combination of bacilli and chemicalinsecticides, resp., but rather to an effect of stimulation.

With the use of a subtle or reduced base of an insecticide a weakeningof the treated insect is to be observed, which promotes the infection bymeans of the micro organism. The weakening of the insect is broughtabout by the fact that the hemocytes are either pathologically changedor directly destroyed by the insecticide, thus blocking phagocytosis.Phagocytosis is the most important defensive mechanism of an affectedinsect against the intruding micro organism. In the course of thisprocess the hemocytes encircle the hyphae which have penetrated into thebody cavity and dissolve them. This mechanism is hampered due to theweakening by means of the insecticide which destroys thehemocyte-system, thus preventing the hemocytes from intercepting thefungus. In addition to that a further working mechanism supports theeffect of the micro organism according to the invention, i.e. the factthat pathogenic bacteria, cocci or rod-shaped bacilli from the intestinepenetrate into the hemolymph after the destruction of the hemocytes,thus entailing septicemia of the pest.

The agent according to the invention is not only effective againstnon-resistant pests but also against pests which have already gotresistant, and this with a considerably smaller and already harmlessdose of chemical insecticide. It is also remarkable that the presentinvention may be applied to all stages of development of the pest, e.g.the pupa, the larva, as well as to hatched insects, with equally goodresults.

The cultures of fungi for the mycelium which is used according to theinvention may be prepared either according to the submersion process oraccording to the surface process. The first method requires aconsiderable expenditure of apparatus and careful handling, especiallywith regard to the preparation of the nutritive substrate and withregard to aeration as well as maintenance of the optimal conditionsconcerning temperature and pA-value.

According to the surface process the insecto-pathogenic fungi arefermented on porous materials, such as bran, whole meal, oat flakes,etc., mixed with water. The preparation of fungi-bran is described inUllmann, Enzyklopaedie der techn. Chemie, 1956, volume 7. pp. 407-408.

The fermentation of fungi of the muscardine type and the preparation ofthe mycelium are described in detail in the Austrian patentspecification OPS No. 262693. The use of bran, whole meal, oat flakes orbread crumbs enables the culture of virulent pathogenic agents of thefungus. The mentioned substrates are not only rich in vitamins acting asgrowth factors but also--like the destroyed pests--in phosphate, enzymes(factors of infection) and amino-acids as metabolic factors, thusenabling the culture of virulent insecto-pathogenic fungi inconsiderable quantities and the mass production of their spores at alarge technical scale in culture tanks. Not only the spores, but thewhole fungus, i.e. the nutritive substrate turned into fungus material,is obtained. Thus the whole culture is regained and can be used for theextirpation of the pests.

At first a pre-culture for the inoculation of the main culture isprepared. The substrate is mixed with water and sterilised. Thenutritive substrate is agitated to obtain a fluffy mass with a largesurface. The containers for the cultures are to be chosen with asuitable capacity in order to ensure a sufficient air space above theculture. Then the culture is inoculated with the spores. The inoculatedculture is fermented over a period of several days at temperatures whichare optimal for the respective fungus (between 26° and 28° C.). Thesubstrate changes into a homogenous mass of fungi and spores, which isused for the inoculation of larger cultures. Inoculation andfermentation of the cultures at a large technical scale are carried outin the same way as is done with the pre-culture, After fermentation theprepared fungus material is dried and pulverized.

The produce is either mixed with the usual extenders or processed into asolution containing wetting materials. It is essential that the entirenutritive substrate is turned into mycelium. According to the inventionthe mycelium is used in combination with a conventional insecticide.

The invention on hand is illustrated by means of control tests which areset out in the following tables. These tests are laboratory tests, forwhich the larva 1 of the potatoe beetle, the potatoe beetle itself andthe cabbage aphid were put into preserving jars together with wateredpotatoe haulm. In each jar there were 50 test insects. The tests werecarried out by treating the pests with a mixture of DDT and Beauveriabassiana. For the control tests they were treated only with either DDTor Beauveria bassiana.

    ______________________________________                                                          mortality rate                                                                            mortality rate if                                    mortality rate                                                                             if treated with                                                                           treated with 0.008%                                  if treated with                                                                            0.5% by weight                                                                            by weight of DDT                                     0.008% by weight                                                                           of Beauveria                                                                              and 0.5% by weight of                           days of DDT       bassiana    Beauveria bassiana                              ______________________________________                                        (I) larve 1 of the potatoe beetle                                             2    10           0           49                                              4    15           3           50                                              6    15           10          54                                              8    31           32          65                                              10   40           35          65                                              12   40           40          76                                              (II) potatoe beetle                                                           2    2            0           8                                               4    2            0           15                                              6    2            0           20                                              8    4            0           32                                              10   8            0           45                                              12   10           0           50                                              14   10           0           72                                              (III) Cabbage aphid                                                           2    12           10          92                                              4    15           12          98                                              6    18           15          100                                             8    19           18                                                          10   22           20                                                          12   30           27                                                          ______________________________________                                    

Further tests were carried out with combinations of Beauveria bassiana,Metarrhizium anisopliae and Paecilomyces farinosus with DDT, E605,Phosdrin and Metasystox. The test insects were potatoe beetles, turnipsawflies, several kinds of greenflies, cabbage caterpillars, smallspruce sawflies, large brown weevils, cabbage moths and bark beetles.

The values given in tables I to III illustrate the effect of theinvention on one of the most persistant pests. Correspondingly betterresults were achieved with less persistant insects.

With the combination of the fungus with E605 at a concentration of0.0001% a mortality rate of 65% was achieved at the 6th day and amortality rate of 89% after 11 days. The control values for the use ofeither E605 or fungus were 31.2% and 43%. In the case of the turnipsawfly, the greenfly, the bean aphid and the peach greenfly (Myzodespersicae) a mortality rate of 100% was achieved already after three dayswith a combination of 0.001% DDT end 0.08% fungus, thanks to theinvention.

The invention at issue will now be illustrated by some examples for theapplication of the method in outdoor tests.

EXAMPLE 1

A field of 1 ha (2.4711 acres) contaminated with potatoe beetles wasdivided into four areas of equal dimensions. One quarter of the fieldwas sprayed with an aqueous solution of 2 g DDT/100 ml water. The secondpart of the field was treated with a mixture of 1 g DDT and 1 g E605 in100 ml of water. The third part was sprayed with an aqueous solution ofBeauveria bassiana at a concentration of 0.6 g fungus/100 ml water. Thelast part was sprayed with the agent according to the invention at aconcentration of 0.1 g. Beauveria bassiana and 0.0005 g DDT. Each partwas treated with 120 l of pest control agent. The mortality rates wereascertained for one square meter of each of the four parts:

    ______________________________________                                        DDT                  2%                                                       DDT + E605           7%                                                       Beauveria bassiana  28%                                                       DDT + Beauveria bassiana                                                                          68%                                                       ______________________________________                                    

Spraying was repeated on the following day. With the mixture ofBeauveria bassiana and DDT the mortality rate was increased to 85%,whereas no improvement was achieved by the other three sprayings.

EXAMPLE 2

Similar to example 1 with the difference that each part was powderedwith 12 kg of a mixture of the pest control agent with powdered talc.

    ______________________________________                                        (A)   2 g DDT/100 g powdered talc                                                                             1.8%                                                mortality rate                                                          (B)   1 g DDT + 1 g E605/10 g powdered talc                                                                   8.4%                                                mortality rate                                                          (C)   0.8 g Beauveria bassiana/10 g powdered talc                                                             27.3%                                               mortality rate                                                          (D)   0.5 g Beauveria bassiana + 0.01 g DDT/10 g                                                               65%                                                powdered talc                                                                 mortality rate                                                          ______________________________________                                    

A second powdering resulted in an increase of the mortality rate to 83%.

EXAMPLES 3 TO 8

Further mixtures of insecto-pathogenic fungi and chemical insecticideswere prepared and the mortality rates were ascertained. The results aregiven in the following table:

    ______________________________________                                                            proportion of the                                                             quantity of micro                                                             organism and the                                                              quantity of insecticide/                                                                      mortality                                 micro organism                                                                          insecticide                                                                             100 ml water    rate                                      ______________________________________                                        Paecilomyces                                                                            Phosdrin  0.6:0.006       70:100%                                   farinosus                                                                     Beauveria DDT       0.5:0.005       80:100%                                   bassiana                                                                      Beauveria HCH       0.5:0.005       80:100%                                   bassiana                                                                      Metarrhizium                                                                            DDT       0.5:0.005       80:100%                                   anisopliae                                                                    Bacillus  DDT        1:0.05         60:100%                                   thueriengiensis                                                               ______________________________________                                    

We claim:
 1. An insecticidal composition for killing pests havinghemolytic systems, comprisinga combination of DDT and a mycelium ofBeauveria bassiana fungus to produce an effect of stimulation in saidpests, and an agriculturally acceptable carrier, said DDT being in therange of about 0.001 to about 0.008 percent by weight and sufficient toimpair the hemolytic systems of said pests, thereby weakening said pestsby affecting the antimicrobial defenses thereof, said mycelium being inthe range of about 0.08 to about 0.5 percent by weight at a levelsuitable for killing said pests having impaired hemolytic systems. 2.The insecticidal composition of claim 1, wherein said DDT is about 0.008percent by weight and said mycelium is about 0.5 percent by weight. 3.An insecticidal composition of claim 1, wherein said carrier is selectedfrom the group consisting of water, talc, bran, whole meal, oat flakesand bread crumbs.
 4. An insecticidal composition for killing pestshaving hemolytic systems, comprisinga combination of 0.0005 grams of DDTper 100 milliliter of water and 0.1 gram of a mycelium of Beauveriabassiana fungus per 100 milliliter of water to produce an effect ofstimulation in said pests, whereby said DDT impairs the hemolyticsystems of said pests and said mycelium kills said pests having impairedhemolytic systems.
 5. An insecticidal composition for killing pestshaving hemolytic systems, comprisinga combination of 0.01 gram of DDTper 10 grams of powdered talc and 0.5 gram of a mycelium of Beauveriabassiana fungus per ten grams of powdered talc, whereby said DDT impairsthe hemolytic systems of said pests and said mycelium kills said pestshaving impaired hemolytic systems.